es ( 44 %) and does not implicate any increased risk of lung cancer . In such lesions , sampling of necrotic areas can result in an inconclusive specimen and lead to necessity of sometimes multiple sampling procedures . In a recent retrospective analysis , positron emission tomography ( PET )/ CT guided FNA has shown some degree of relationship to accuracy of results . 17 This approach could improve the yield of sampling in lung masses with necrotic areas .
Despite the high sensitivities of these minimally invasive procedures , approach to a “ non-diagnostic ” specimen remains a challenge . Studies that considered “ non-diagnostic , non-specific , and inconclusive ” results from TTNA as negative reported high negative predictive value ( NPV ) of the test for malignancy . 18-19 Although larger target lesions have been shown to provide adequate samples more often , this adequacy does not translate into 18 , 20 an improvement of NPV .
Figure 1a . Granulomatous disease : One 20x field shows numerous histiocytes forming loose non-epithelioid , non-necrotizing granulomas . Mixed inflammation ( lymphocytes , plasma cells and scant neutrophils ) is present in the background with occasional giant cell formation ( arrow head ). [ H & E ]
Prompt tissue diagnosis is imperative . Minimally invasive techniques have evolved with EBUS-TBNA and TTNA , which can diagnose and stage lung cancer . These minimally invasive procedures have a high sensitivity and the yields for both trans-bronchial and transthoracic needle sampling are higher for larger lung nodules . 13-15 Recently , ultrasound guided percutaneous fine needle aspiration ( FNA ) of peripheral lung lesions was investigated . 16 The procedure has yield and complication rates comparable to CT guided needle aspiration with the advantage of portability and convenience without radiation exposure . It is important to note that despite the lower complication rates of minimally invasive techniques , surgical resection remains the gold standard for workup of masses highly suspicious for malignancy . The choice of method depends on the cardiopulmonary risk factors of the patient , patient preference and institutional variability of feasibility of either approach .
Special considerations during work up of lung masses
The CT findings from our study can guide the choice of using further noninvasive testing to complement tissue sampling . A large mass has significantly different characteristics on imaging compared to a lung nodule . Our data indicates that necrosis is often present in large lung mass-
A repeat sampling must be performed by a same or different method in case of inconclusive results for a lung mass until a final diagnosis is established . The exception to above statement is that a granulomatous inflammation with no apparent cause ( negative tissue , sputum , and serum work up for fungal or mycobacterial etiology ; sarcoid ; and granulomatosis with polyangiitis , etc .) can be followed with serial CT scans over time if history and clinical features dictate low risk of malignancy . The inflammatory groups in our study were sampled an average of three times before they were finally simply followed up , even though there were histologic and culture evidence of an alternative diagnosis . The large size of the mass was simply that disconcerting , and even the infectious disease physicians requested for a “ better biopsy ” in many cases . Geographical factors , when present , could
Figure 1b . Small round blue cell tumor : One 20x field shows sheets and clusters of small round blue cells with scant cytoplasm infiltrating eosinophilic fibrous tissue . Marked crush artifact ( arrow ) along with nuclear pleomorphism and nuclear molding ( arrow heads ) is seen . [ H & E ]
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